fix: declare click as an explicit runtime dependency

[Dongbumlee]

Summary

Declares click as an explicit runtime dependency so a clean pip install agentops-accelerator no longer crashes on the explain / manual commands.

Problem

The CLI imports click directly for its pager and manual output paths (app.py _emit_manual_output / _emit_doctor_explain). click was only available transitively via Typer, but Typer 0.26+ no longer depends on click. As a result, a fresh install of the published agentops-accelerator (0.3.11) crashes:

\
$ agentops explain
ModuleNotFoundError: No module named 'click'
\\

This affects agentops explain, agentops init explain, and agentops doctor explain (all formats/flags). It was masked in dev/editable installs and when the [foundry] extra is installed (which pulls click transitively), but the base install is broken.

Fix

Add click>=8.1,<9 to [project].dependencies in pyproject.toml.

Verification

Found via a full E2E test of the published 0.3.11 package in a fresh venv (44-case command/parameter matrix). Fix verified by building the wheel from this branch and installing it into a brand-new clean venv: click is pulled automatically and both agentops explain and agentops doctor explain exit 0.

No version bump (setuptools-scm owns versioning). Changelog updated under [Unreleased] > Fixed.